This application claims the priority of Japanese Patent Application No. 2000-259546 filed Aug. 29, 2000 in Japan, the entire contents of which are herein incorporated by reference.
1. Field of the Invention
The present invention is directed to a magnetic carrying device and, more particularly, it relates to a magnetic carrying device configured to transmit rotational power using a non-contact method and suitable for a drive mechanism to carry a carrier in a plurality of processing chambers linearly linked in a vacuum atmosphere.
2. Discussion of Related Art
In the description of the background of the present invention that follows reference is made to certain structures and methods, however, such references should not necessarily be construed as an admission that these structures and methods qualify as prior art under the applicable statutory provisions. Applicants reserve the right to demonstrate that any of the referenced subject matter does not constitute prior art with regard to the present invention.
Previously, contact transmission-type drive mechanisms have carried objects in a vacuum environment using, for example, a rack and pinion mechanism or a roller-type drive method. The friction coefficient in a drive mechanism can be large and a lubricant cannot be used due to the vacuum requirements. As a result, the amount of wear on drive components and the amount of dust generated can deleteriously impact manufacturing operations, particularly in the fields of semiconductors and electronic parts manufacturing.
For example, excessive levels of dust can lower the yield and throughput in the manufacturing of devices. Therefore, it is desirable to maximize the reduction of dust by, for example, minimizing dust generation. Further, with the advent of high speed manufacturing processes, high throughputs, and high-density devices, the demand for low dust production has increased. Additionally, in previous contact mechanisms, clearance between the contacting parts must be large because the friction coefficient is large, thereby limiting the minuteness of the operations that may be performed.
A non-contact type carrying system can be used to reduce dust. Amongst the various methods proposed to reduce dust, the use of magnetic coupling action (hereinbelow referred to as a xe2x80x9cmagnetic carrying devicexe2x80x9d) is comparatively simple. A combined spiral magnetic circuit and magnetic pole is disclosed in U.S. Pat. No. 5,377,816. In addition, Japanese Unexamined Patent Application No. Heisei 10-205604 discloses, a magnetic carrying device for carrying a carrier without contact.
However, when a carrier on a magnetic carrying device passes through a plurality of processing chambers, generally separated by a gate linking structure, the drive shaft which carries the carrier is separated by partition sections (partition valves) corresponding to each processing chamber and the magnetic circuits between the drive shafts must be synchronized. Therefore, although the problems of wear and dust generation can be reduced by the previous magnetic carrying device compared to a contact transmission method, the synchronizing operation between the carrier magnet and the position of the drive shafts of adjacent processing chambers is difficult.
Japanese Unexamined Patent Application No. Heisei 10-159934, discloses a method for the smooth transfer of a carrier between a plurality of vacuum processing chambers separated and directly connected with a linking part. A rotation drive device with a magnetic coupling part divided into a fixed section and mobile section, absorbs the disparity between the drive shafts of adjacent processing chambers. The disclosed device has a drive power transmission using a bevel gear mechanism, and has a carry speed based on a rotation of the order of 2000 pps (pulse per sec: 500 pps/1 rotation, at 4 rotations/second) acts as a drive power transmission.
However, in recent years, high speed thruput has increased and highspeed magnetic carrying devices now perform at 10000 pps or above. At such high speeds, a condition occurs in which the magnetic coupling does not maintain the necessary speed in the direction of transport and magnets of the same polarity can come into proximity with each other. Under such conditions, the magnets repel each other, the carrier is stopped, and hunting (vibration) occurs between the carrier and the rotation drive device for the adjacent processing chamber. This hunting is a factor in the unsettling of the carrier leading to, for example, the object for processing falling off the mount, both magnetic coupling sections losing magnetism, or the generation of disparities in the stationary position of the carrier in the processing chamber.
Further, in the divided spiral magnetic coupling, smooth operation is maintained by the use of grease frequently applied on the slide part, which negatively impacts productivity and operations.
An object of the present invention is to provide a magnetic carrying device that is particularly suited for application in a semiconductor manufacturing device or electronic part manufacturing device or the like which comprises a plurality of chambers connected in parallel. The magnetic carrying device is designed to transport carriers between adjacent processing chambers smoothly and continuously at high speed, thereby improving productivity.
According to one embodiment of the present invention, a magnetic carrying device is provided for carrying an object to be processed through a plurality of chambers that are separated from each other by an openable linking part. The magnetic carrying device comprises a carrier having a plurality of carrier magnetic coupling parts at a slide end; a rotating drive member arranged in each of the plurality of chambers, each rotating drive member having an outer surface with a spiral magnetic coupling part having a N pole spiral part and a S pole spiral part, the N pole spiral part being arranged at a first interval from the S pole spiral part; a drive device; a power transmission part arranged to transmit a drive force from the drive device to the rotating drive members; the carrier magnetic coupling parts being spaced from each other a distance substantially equal to the first interval; a guide device slidably supporting the carrier along a path at a spaced relationship from the rotating drive members so that the carrier is moved along the guide device by a rotating motion of the rotating drive members; a control member provided to synchronously control the rotating drive members to provide a continuous operation of the carrier between the chambers; wherein the rotating drive members are spaced from each other at intervals equal to a distance defined by 2 X the first interval X a positive whole number integer.
In another aspect of the invention, the rotating drive members may be exterior to the chambers.
Furthermore, the spacing of the rotating drive members may have an acceptable tolerance of xc2x11.5 mm.
In a further aspect of the invention, each of the rotating drive members may be divided into a first section and a second section and the power transmission part may be disposed between the first section and the second section.
In addition, the drive device may be a pulse motor and the control member controls an operation of the pulse motor by pulse number control.
A matching of the rotating drive members may have a total disparity of xc2x130xc2x0 or a matching of the rotating drive members may have a total disparity of xc2x118.2xc2x0.